The starting problem may
be due to a dead battery, a loose or corroded battery
cable, a bad ignition switch, an open neutral safety
switch, or a bad solenoid or starter.

Total silence usually
means nothing is getting through to the starter. So
start with the battery to check if it has a full charge
or if the battery cables get loose, corroded or damaged?
Be sure to check both ends of the cables, including
the starter and ground connections.

If you don't find any
obvious problems with the battery or its connections,
voltage may not be passing through the ignition switch
circuit to the starter solenoid. A voltmeter or 12 volt
test light can help you see if voltage is reaching the
solenoid when you turn the key.

If voltage isn't getting
through, try jiggling the gear shift lever. Some vehicles
may also have a safety switch on the clutch pedal that
prevents the engine from starting unless the clutch
pedal is depressed. Use your voltmeter or test light
to isolate the component that needs to be replaced or
adjusted. Sometimes the transmission or clutch linkage
may need to be adjusted for the safety switch to work
properly.

If voltage is getting
through the ignition switch circuit, but the starter
isn't doing anything, check the wiring connections on
the solenoid and starter. Are they clean and tight?
Try bypassing the solenoid. Refer to a shop manual for
the proper terminals, then jump the one that routes
voltage directly to the starter (usually B+ or BAT).
If the starter spins, the problem is a bad solenoid
(or poorly grounded solenoid). If nothing happens, the
problem is a bad starter that needs to be replaced.

When
the starting key is turned, nothing happens but only
a clicking sound. Is a newstarter needed?

Solution:

The only way to know for sure is to check
out the battery, solenoid and starter. If you hear a
clicking noise, it means voltage is getting through
to the solenoid. But there may not be enough voltage
to spin the starter. So start with the battery and cables.

Is the battery at full charge? Are the
battery cables clean and tight? Be sure to check both
ends. Are the other electrical connections at the solenoid
and starter clean and tight? It doesn't take much corrosion
to choke off the flow of amps to the starter.

Next, check the wiring connections on
the solenoid and starter. Are they clean and tight?
Also check the solenoid ground connection or its mounting.
Rust or corrosion here can interfere with the flow of
amps, too.

Try bypassing the solenoid to see if the
starter spins. If it spins, the problem is excessive
resistance in the solenoid. Replace the solenoid. If
the starter doesn't spin, or turns very slowly, however,
the starter is dragging and needs to be replaced.

Check one of two problems: Either the
starter drive on your starter is defective and is not
engaging the flywheel to crank the engine, or the flywheel
has some broken or damaged teeth that are preventing
the starter from engaging.

Starters come in a variety of designs.
On some, the solenoid is mounted on top of the starter
(direct drive). When the key is turned, the solenoid
routes current to the starter motor and at the same
time pulls a lever that slides the drive gear mechanism
out so it will engage the flywheel and crank the engine.
If the solenoid is weak or damaged, it may not be strong
enough to overcome the spring tension that retracts
the drive gear. So the starter spins but doesn't crank
the engine.

On other starters, the solenoid is mounted
remotely. When the starter motor starts to spin, it
ratchets out so the drive gear will engage the flywheel
and crank the engine. If the drive mechanism is damaged
or hung up, the motor may spin but not crank the engine.

Regardless of what type of starter you
have, it will have to come out for further inspection.
The drive gear (which is sometimes referred to as a
"Bendix drive") should move out when the starter
starts to spin. The drive gear usually has a one-way
clutch that is supposed to protect the starter against
damage if someone keeps cranking the engine once it
starts. The gear should turn one way but not the other.
If the gear is locked up or turns freely either way,
the drive is bad and needs to be replaced. If the drive
can't be replaced separately, you'll have to replace
the entire starter.

STARTER TESTING

If the drive seems okay, the starter should
be "bench tested" using jumper cables or special
equipment designed for this purpose.

CAUTION: Be careful because a starter
develops a lot of torque. It should be held down with
a strap or clamped in a vice (be careful not to crush
or deform the housing!) before voltage is applied.

A simple no-load bench test can be performed
with a battery and a pair of jumper cables to see if
a starter motor will spin. But this test alone won't
tell you if the starter is good or bad because a weak
starter that lacks sufficient power to crank an engine
at the proper speed (usually a minimum of 250 to 500
rpm) may still spin up to several thousand rpm when
voltage is applied with no load.

A better method of determining a starter's
condition is to have it tested on equipment that measures
the starter's "amp draw." A good starter should
normally draw a current of 60 to 150 amps, depending
on the size or power rating of the starter. Some "high
torque" GM starters may draw up to 250 amps, so
refer to the OEM specifications to make sure the amp
draw is within the acceptable range.

If the starter does not spin freely, or
draws an unusually high or low number of amps, it is
defective and replacement is required.

An unusually high current draw and low
free turning speed typically indicate a shorted armature,
grounded armature or field coils, or excessive friction
within the starter itself (dirty, worn or binding bearings
or bushings, a bent armature shaft or contact between
the armature and field coils). The magnets in permanent
magnet starters can sometimes break or separate from
the housing and drag against the armature.

A starter that does not turn and draws
a high current may have a ground in the terminal or
field coils, or a frozen armature.

Failure to spin and zero current draw
indicates an open field circuit, open armature coils,
defective brushes or a defective solenoid.

Check one of two problems: a fuel line
restriction or an exhaust restriction.

FUEL RESTRICTION

A plugged fuel filter, crushed fuel line
or clogged pickup screen inside the fuel tank can all
starve your engine for fuel. Enough fuel may get through
for the engine to start and run at low speed, but when
more fuel is needed it can't get through resulting in
loss of power at high speed. The same kind of problem
can also be caused by a weak fuel pump. But fuel pumps
usually quit altogether when they fail.

Inspect the fuel line from the tank to
the engine. If you don't see any obvious damage, try
replacing the fuel filter. If that doesn't help, blowing
out the fuel line with compressed air from the engine
towards the fuel tank may help dislodge a blockage and
debris from the pickup screen. If the pickup screen
in the tank is clogged with rust and debris, the tank
will have to be removed so the screen can be replaced
and the tank cleaned.

Fuel pressure can also be checked by teeing
a suitable gauge into the fuel line. If pressure is
very low (refer to a manual for the specs), the pump
probably will need to be replaced.

EXHAUST RESTRICTION

As for an exhaust restriction, the easiest
way to check for this condition is to hook up a vacuum
gauge to a vacuum port on the intake manifold or throttle
body. If vacuum is low and continues to drop as the
engine runs, it's telling you pressure is backing up
because of a restriction in the exhaust. The most likely
culprit is a clogged catalytic converter.

If the converter has overheated, it may
have melted internally. This would restrict the flow
of gases through the converter and create a serious
backpressure problem that would cause a loss of power
at high speed. If the blockage is complete, the engine
may start then die and not run at all.

Other causes here may include a crushed
exhaust pipe (a visual inspection should find this easy
enough), a double-walled pipe that has collapsed internally,
or a muffler that has become clogged with rust (rare,
because they usually blow out). If you suspect an exhaust
restriction, temporarily disconnect the head pipe from
the catalytic converter (which is no easy task because
the bolts will probably be rusted solid). If the engine
now runs normally, you have an exhaust restriction.
Inspect the converter and replace it if needed.

NOTE: If the converter is plugged, it
failed because something else caused it to overheat.
Causes include misfiring spark plugs and leaky exhaust
valves. The underlying problem needs to be identified
and corrected before the converter is replaced otherwise
the new converter will suffer the same fate.

It may be an exhaust blockage, probably
due to a clogged catalytic converter. The converter
can overheat and be damaged if excessive amounts of
unburned fuel enter the exhaust system. This can happen
if the engine has one or more fouled spark plugs or
leaky exhaust valves. When this unburned fuel hits the
converter, it sends temperatures soaring. The ceramic
substrate or pellets that support the catalyst can melt
and partially or completely block the flow of exhaust
through the converter.

If a complete blockage occurs, the engine
will start normally but the exhaust has no place to
go. Backpressure quickly builds up and within a couple
of minutes the engine quits running. Eventually, the
pressure will seep out and allow the engine to restart
after it has sit for some time. But the blockage will
prevent it from running for long.

The cure here would be to replace the
converter. But first, the underlying problem that caused
the converter to overheat and fail needs to be diagnosed
and corrected -- otherwise the new converter will suffer
the same fate.

Other possible causes of this kind of
condition include a crushed exhaust pipe, some prankster
shoving a potato up your tailpipe, a collapsed inner
wall in a double-walled head pipe, or a muffler that's
obstructed with rust debris.

The
engine won't start. It cranks normally, but just won't
go.

Solution:

It may be an ignition, fuel delivery or
compression problem.

1. Check for spark first. If there's no
spark, you may have a failed ignition module, ignition
pickup, ignition coil or open in the ignition circuit
(bad ignition switch or neutral safety switch).

2. If you have spark, check for fuel.
On carbureted engines, remove the air cleaner, hold
the choke open, look down the carburetor throat and
work the throttle linkage. If you don't see any fuel
squirting into the carburetor, the problem may be a
stuck needle inlet valve in the carburetor, a bad fuel
pump, a plugged fuel filter, a plugged or frozen fuel
line, an obstructed fuel tank pickup screen, or no fuel
(or water contaminated fuel) in your tank.

3. If you have spark and fuel, your timing
chain or belt may have broken or slipped. If your engine
has a distributor, remove the distributor cap and see
if the rotor turns when the engine is cranked. No movement
would tell you the timing belt or chain (or possibly
the cam itself) is broken. Another alternative is to
remove the valve cover to see if the valves are opening
and closing. This too will show you if the cam drive
or cam is broken.

If a cam belt or chain has "slipped
a tooth," throwing valve timing off, the valves
will still open and close, and the rotor inside the
distributor will still turn. But the engine won't develop
enough compression to start. A compression check can
help you find this kind of problem.

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last modified:Feb 05 2002